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Abstract:

A method for manufacturing an injection molded product includes producing
an injection mold by building a one-piece mold block including a mold
cavity sized and shaped to correspond to a desired shape of the injection
molded product and a first feeder duct extending from the mold cavity and
injecting a molten material into the mold cavity via the feeder duct to
form an injection molded product and a sprue extending therefrom into the
first feeder duct in combination with machining a portion of the
injection block to expose the injection molded product and machining the
injection molded product while the sprue firmly holds the product in a
remaining portion of the injection mold. The product is then cut from the
sprue.

Claims:

1. A method for manufacturing an injection molded product, comprising:
producing an injection mold by building a one-piece mold block including
a mold cavity sized and shaped to correspond to a desired shape of the
injection molded product and a first feeder duct extending from the mold
cavity; injecting a molten material into the mold cavity via the feeder
duct to form an injection molded product and a sprue extending therefrom
into the first feeder duct; machining a portion of the injection block to
expose the injection molded product; machining the injection molded
product while the sprue firmly holds the product in a remaining portion
of the injection mold; and cutting the injection molded product from the
sprue.

2. The method according to claim 1, wherein the machining of the
injection molded product includes smoothing an outer surface of the
product.

3. The method according to claim 1, wherein the mold block is fixedly
built up on a base plate.

4. The method according to claim 1, wherein the mold block includes a
second feeder duct.

5. The method according to claim 4, wherein the base plate comprises a
first surface adjacent to the mold block, a second surface facing away
from the mold block and an inflow channel in fluid communication with the
first feeder duct, the inflow channel having an enlarged portion toward
the second surface of the base plate.

6. The method according to claim 1, wherein the mold block is formed by
depositing a laser melted metallic powder layer by layer.

7. The method according to claim 1, wherein a metallic structure is
inserted into the mold cavity during production of the mold block to
provide support to the injection molded product.

8. The method according to claim 1, wherein a metallic insert is inserted
into the mold cavity during production of the mold block such that a
threading is machinable through the insert into the injection molded
product.

9. The method according to claim 1, wherein the machining of the product
includes one of a milling of the product and a cutting of threads into
the product.

10. The method according to claim 1, wherein producing the injection mold
includes producing one of an air and material outlet and a coolant duct.

11. A method for manufacturing an injection molded product, comprising:
producing an injection mold including a lower part and an upper part
forming a mold cavity therebetween sized and shaped to correspond to a
desired size and shape of a product to be injection molded therein, a
first feeder duct extending from the mold cavity into the lower part;
injecting a molten material into through the first feeder duct into the
mold cavity to form an injection molded product and a sprue extending
therefrom into the first feeder duct; removing the upper part of the
injection mold to expose a portion of the injection molded product;
machining a portion of the lower part of the injection mold to expose a
remaining portion of the product; machining the injection molded product
while the sprue firmly holds the product in a remaining portion of the
lower part of the injection mold; and cutting the injection molded
product from the sprue.

12. The method according to claim 11, wherein the injection mold is
produced using a selective laser melting procedure.

13. The method according to claim 11, wherein the machining of the
injection molded product includes smoothing an outer surface of the
product.

14. The method according to claim 11, wherein the injection mold is
fixedly built up on a base plate.

15. The method according to claim 11, wherein the injection molded
product includes a second feeder duct.

16. The method according to claim 15, wherein the base plate includes a
first surface adjacent the injection mold, a second surface facing away
from the base plate and an inflow channel in fluid communication with the
first feeder duct, the inflow channel having an enlarged portion toward
the second surface.

17. An injection mold system, comprising: a mold block including a mold
cavity sized and shaped to correspond to a desired size and shape of a
product to be injection molded therein and a first feeder duct extending
into the mold cavity such that injection of a molten material
therethrough to the mold cavity forms the injection molded product with a
sprue extending therefrom into the first feeder duct.

18. The injection mold system according to claim 17, wherein the mold
block is formed as a single unit.

19. The injection mold system according to claim 17, wherein the mold
block includes a lower part and an upper part fixed to one another such
that the mold cavity is formed therebetween.

20. The injection mold system of claim 17, further comprising: a base
plate having a first surface attached to the mold block and a second
surface facing away from the mold block, the base plate including an
inflow channel in fluid communication with the first feeder duct such
that the sprue is held within the inflow channel.

[0002] The present invention relates generally to a method for
manufacturing a product by injection molding.

BACKGROUND

[0003] One problem associated with known injection molds is that usually a
two part mold is configured in such a way that a product formed in the
mold is not held in either part of the two part mold so that the product
must be fixed to a machine by particular holding, gripping or fixation
devices for further machining. Thus, there remains a need for an improved
method for manufacturing a product by injection molding with an injection
mold which permits machining or a removal of a portion of the injection
mold so that the product is firmly held in the remaining part of the
injection mold and can be further processed or machined without the need
for additional holding, gripping or fixation devices.

SUMMARY OF THE INVENTION

[0004] The present invention relates to a method for manufacturing an
injection-molded product. The exemplary method according to the invention
comprises the steps of producing an injection mold by building up layer
by layer a one-piece mold block including a mold cavity sized and shaped
to correspond to a desired product to be formed by injection molding and
injecting a molten material into the injection mold and cooling off the
injected molten material so that an injection molded product is formed.
The injection mold is machined after cooling off of the product to remove
a portion of the injection mold necessary to completely expose the
product. The product is then machined while being firmly held in a
remaining part of the injection mold via one or more sprues extending
therefrom. The product is then cut off from the one or more sprues.

[0005] Exemplary molding materials for the product according to the
invention include PEEK, reinforced plastic and injectable metal alloys.

[0006] The method according to the exemplary embodiment of the present
invention may speed production of individual products (e.g., implants)
with the injection molding technique and may further permit an injection
mold to be quickly produced for an individual product without the need
for a pattern of the product to be molded. The method according to the
invention may also allow the molded product to be machined (e.g. by
milling) without the need for further holding, gripping or fixation
devices and will makes a two part mold unnecessary due to the
configuration of the injection mold as a lost mold. Furthermore,
injection and coolant ducts can be individually configured and the mold
may be mounted on an interface plate suitable as a base for different
machines.

[0007] In one exemplary embodiment, the machining of the product includes
producing a smooth outer surface on the product by milling to permit use
thereof as a medical implant. Holes and threads may be machined into the
product as required for particular procedures. Furthermore, the exemplary
milling system and method permits the productions of structures that are
too coarse to be injection molded, as those skilled in the art will
understand.

[0008] In a further exemplary embodiment of the method the injection mold
may be produced such that it is fixedly built up on a base plate. This
configuration has the advantage that the base plate may act as an
interface for different machines (e.g., the injection molding machine, a
milling machine, etc.).

[0009] In a further exemplary method, the production of the injection mold
may include the production of one or more feeder ducts. Thus, the
injection mold may be completely finished via layer-by-layer deposition
so that no subsequent processing or machining is necessary.

[0010] In another exemplary method, the base plate comprises a first
surface facing the injection mold, a second surface facing away from the
injection mold and one or more inflow channels in fluid communication
with the one or more feeder ducts. The inflow channels have an enlarged
cross-section towards the second surface of the base plate. The enlarged
cross-section permits the one or more sprues to be form-fittingly and
rigidly gripped in the base plate so that the product can be rigidly held
in the remaining part of the injection mold and the base plate. The
inflow channels may have a cylindrical or conical portion.

[0011] In another exemplary method, the layer-by-layer deposition may be
performed by "direct additive laser manufacturing", which requires
depositing a laser melted metallic powder.

[0012] In yet another exemplary method, one or more metallic structures
may be introduced into the injection mold during production of the
injection mold. The metallic structure may provide an integrated support
in the finished product to improve the mechanical stability of the
product.

[0013] In still another exemplary method, one or more metallic inserts may
be introduced into the injection mold during production of the injection
mold. The metallic inserts may be firmly anchored within the product.

[0014] In a further exemplary method, the machining of the product may
include milling of the product and/or cutting threads into the one or
more metallic inserts.

[0015] In a further exemplary method, the production of the injection mold
may include the production of one or more air and material outlets and
one or more coolant ducts.

[0016] According to a further exemplary embodiment of the present
invention, there is provided a method for manufacturing an injection
molded product comprising the step of producing an injection mold in the
form of a two part mold including a lower and an upper part forming a
mold cavity therebetween configured to form a desired product by
injection molding. A molten material is injected into the injection mold
and cooled to form the desired product. The upper part of the two-part
mold is removed after cooling of the product. The lower part of the
injection mold is machined to remove a portion of the injection mold
necessary to completely expose the product. The product is machined while
being firmly held in a remaining part of the lower part of the injection
mold via one or more sprues extending therefrom. The product is then cut
from the one or more sprues.

[0017] In one exemplary method, the two-part mold is produced by a
selective laser melting procedure.

[0018] In another exemplary embodiment, the machining of the product
includes producing a smooth outer surface on the product by milling to
permit use thereof as a medical implant. Furthermore, the exemplary
milling system and method permits the productions of structures that are
too coarse to be injection molded, as those skilled in the art will
understand.

[0019] In another exemplary method, the injection mold may be fixedly
built up on a base plate which can be used as an interface for different
machines (e.g., the injection molding machine, a milling machine, etc.).

[0020] In another exemplary method, the production of the injection mold
may include the production of one or more feeder ducts so that the
injection mold can be completely finished via layer-by-layer deposition
without requiring subsequent processing or machining.

[0021] In still another exemplary method, the base plate comprises a first
surface adjacent the injection mold, a second surface facing away from
the injection mold and one or more inflow channels in fluid communication
with the one or more feeder ducts. The inflow channels may have an
enlarged cross-section toward the second surface so that the one or more
sprues are form-fittingly and rigidly gripped in the base plate. Further,
any of the inflow channels may have a cylindrical or conical portion.

[0022] According to another exemplary embodiment of the present invention,
there is provided a method for producing an injection mold comprising the
step of building up layer-by-layer a one-piece mold block including a
mold cavity for forming a desired product by injection molding, one or
more feeder ducts, an air outlet and one or more coolant ducts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Several embodiments of the invention will be described in the
following by way of example and with reference to the accompanying
drawings in which:

[0024]FIG. 1 illustrates a first cross-sectional view of a portion of an
injection mold manufactured according to an exemplary embodiment of the
method according to the present invention;

[0025]FIG. 2 illustrates a second cross-sectional view of the injection
mold of FIG. 1;

[0026]FIG. 3 illustrates a cross section of an injection mold according
to the embodiment of the method of FIG. 1;

[0027]FIG. 4 illustrates a cross section of the injection mold partly
machined according to the embodiment of the method of FIG. 1;

[0028]FIG. 5 illustrates a cross section of the partly machined injection
mold according to the embodiment of the method of FIG. 1;

[0029] FIG. 6 illustrates a cross section of the product and the fully
machined injection mold according to the embodiment of the method of FIG.
1;

[0030] FIG. 7 illustrates a cross section of a two-part injection mold
manufactured according to another exemplary embodiment of the method
according to the present invention;

[0031]FIG. 8 illustrates a cross section of a portion of the lower half
of the injection mold according to the embodiment of the method of FIG.
7;

[0032]FIG. 9 illustrates a cross section of a portion of the upper half
of the injection mold according to the embodiment of the method of FIG.
7; and

[0033]FIG. 10 illustrates a cross section of the completed lower half of
the injection mold according to the embodiment of the method of FIG. 7.

DETAILED DESCRIPTION

[0034] The present invention is directed to a system and method for
producing an injection mold and subsequently drilling the injected mold
without the need for any gripping devices. Specifically, the exemplary
system and method according to the invention is directed to building a
mold block layer-by-layer using a depositing technique known in the art.
While depositing the layers, the feeder duct formed as an elongated
opening is provided in each layer. Once the mold block is complete, a
material injected into the mold will also flow into the feeder duct to
form an elongated sprue extending from the molded product to a base of
the system, thus holding the product in position while milling is
performed. Once the molded product has been milled to required
specifications, the sprue is removed therefrom to free the product from
the base.

[0035] FIGS. 1 to 6 illustrate a first exemplary embodiment of a method
for manufacturing an injection molded product 11 using an injection mold
system 1. The injection mold system 1 comprises a mold block 2 including
a mold cavity 5 built on a base plate 9 such that a portion of the
injection molded product 11 remains fixed to the base plate 9 while the
product 11 is further processed and/or machined. As shown in FIGS. 1 and
2, the mold block 2 of the injection mold system 1 may be built on the
base plate 9 using an additive laser manufacturing process, which builds
the mold block 2 by depositing a laser melted metallic powder thereon,
layer by layer, using a laser additive device 18. For example, a known
device for direct additive laser manufacturing is available from IREPA
LASER, France. It will be understood by those of skill in the art,
however, that any known laser additive device may be used with the system
1. The base plate 9 acts as an interface between the mold block 2 and
various machines and/or devices used during an injection molding process,
connecting the base plate 9 to a machine interface plate 17 of devices
such as, for example, the laser additive device 18, an injection molding
device 21 and/or a machining device (e.g., a milling cutter 23).

[0036] As illustrated in FIG. 1, the base plate 9 is removably fixed to a
machine interface plate 17 of the laser manufacturing apparatus 18 using
fixation elements such as, for example, screws 20. The base plate 9
includes a first surface 25 on which the mold block 2 is built and a
second surface 26 attached to the machine interface plate 17. The base
plate 9 includes inflow channels 24 extending therethrough from the first
surface 25 to the second surface 26 so that mold material may flow
therethrough to the mold block 2. The base plate 9 also includes coolant
ducts 28 extending through at least a portion thereof such that a cooling
liquid may flow between the base plate 9 and the mold block 2. The base
plate 9 may further include an air and material outlet 29 extending
therethrough. As shown in FIGS. 1-3, metallic powder is injected via one
or more nozzles and melted under a high-power laser unit 19 resulting in
a homogenous deposition of the metallic material. The mold block 2 is
built to include feeder ducts 7 for supplying molten material to the mold
cavity 5, a duct the for air and material outlet 6, as shown in FIG. 3,
from the mold cavity 5 and coolant ducts 8 for a cooling liquid during
cooling of the injected molten material. In a preferred embodiment, the
mold block 2 includes two feeder ducts 7. The feeder ducts 7 may be
produced in communication with the inflow channels 24, the coolant ducts
8 in communication with the coolant ducts 28 and the air and materials
outlet 6 in communication with the channel 29 of the base plate 9 so that
the mold block 2 does not require any subsequent processing. To produce
one layer, the nozzles and the high-power laser unit 19 are moved
together along a path covering the complete area of the layer. Thus, the
metallic material is deposited on a surface corresponding to a
cross-section of the respective layer only so that no material is
deposited in the range of the mold cavity 5, the feeder ducts 7, the duct
for air and material outlet 6 and the coolant ducts 8.

[0037] The diameters of the feeder ducts 7 are sufficiently large so that
sprues 15, as shown in FIG. 5, formed by the solidified cast material of
the molded product 11 firmly hold the molded product 11 to the base plate
9 and the machine interface plate 17 during subsequent machining. The
feeder ducts 7 can be distributed over the cross-sectional area of the
mold cavity 5 in such a way that the injection-molded product 11 is held
in a mechanically stable manner via the sprues 15. The inflow channels 24
may have an enlarged cross-section 27 at the second surface 26 of the
base plate 9 so that the sprues 15 formed by the solidified cast material
are held in the base plate 9 in a form-fitting manner.

[0038] As illustrated in FIG. 2 a metal structure 14 and two metallic
inserts 12 may be inserted into the mold cavity 5 of the injection mold
system 1 during manufacturing to provide support to the molded product
11. The metallic inserts 12 may be used to machine threads subsequently
therethrough and into the molded product 11.

[0039] Once the mold block 2 has been built, the injection mold system 1
may be mounted on an injection-molding machine 21, as shown in FIG. 3.
The base plate 9 together with the attached mold block 2 are removably
fixed to a machine interface plate 17' of the injection molding machine
21. The base plate 9 may be attached to the injection-molding machine 21
in a manner similar to the laser additive apparatus 18, as described
above. For example, the base plate 9 may be attached to the
injection-molding machine 21 via screws 20. A molten material 10, e.g.
polyether ether ketone (PEEK), a reinforced plastic or an injectable
metal alloy is injected into the injection mold system 1 through the
inflow channels 24 and the corresponding feeder ducts 7 and into the mold
cavity 5. The molten material 10 is inserted therein until the mold
cavity 5 is completely filled, surrounding the metal structure 14 and the
inserts 12, and so that a portion of the molten material 10 extends into
the duct for air and material outlet 6. After the injection step has been
completed a cooling liquid is pumped through the coolant ducts 8 so that
the injected molten material 10 is cooled off and the product 11 is
formed.

[0040]FIG. 4 illustrates the step of machining the mold block 2 of the
injection mold system 1 after cooling of the product 11. Using, for
example, a milling cutter 22, a portion of the mold block 2 is removed to
completely expose the product 11. The base plate 9 of the injection mold
system 1 may be mounted on a machine interface plate 17'' of a milling
machine 22.

[0041]FIG. 5 illustrates the step of machining the product 11. The
machining of the molded product 11 may be performed on the same milling
machine used during the previous step where the mold block 2 was
machined. The machining of the product 11 includes the cutting of threads
into the metallic inserts 12. A milling tool 23 may be used to produce a
smooth surface on the whole product 11. During machining, the product 11
is firmly held in the remaining part of the mold block 2 and/or the base
plate 9 by the two integrally formed cast sprues 15 which extend from the
molded product within the feeder ducts 7. The cast sprues 15 may further
extend into the enlarged end of the inflow channel 24 such that the
molded product 11 is held firmly relative to the base plate 9. It will be
understood by those of skill in the art that the sprues 15 permit the
molded product 11 to be fixed relative to the injection mold system 1
such that the molded product 11 may be further processed and/or machined
without the use of additional gripping and/or fixation devices.

[0042] Once the molded product 11 has been machined as desired, the molded
product 11 may be detached from the cast sprues 15 such that only the
molded product 11 remains. As shown in FIG. 6, the finished product 11
may be cut from the two sprues 15 using a cutting tool.

[0043] As shown in FIGS. 7 to 10, a second exemplary embodiment of an
injection mold system 1' is substantially similar to the injection mold
system 1, as described above, but uses a selective laser melting process.
The injection mold 1', however, comprises a two part mold 13' including a
lower part 3' and an upper part 4' which together form a mold cavity 5'.
Similar to the injection mold system 1, the two-part mold 13' is built on
a base plate 9' removably fixed to a machine interface plate of a
processing and/or machining device. As illustrated in FIG. 8 the lower
part 3' of the injection mold 1' is built up layer by layer, forming a
first portion of the mold cavity 5' along with the feeder ducts 7' and
the cooler ducts 8, by first scattering a metallic powder over the
complete surface of the lower part 3' to be produced. The metallic powder
is deposited within a casing mounted on a machine interface plate of e.g.
of a NC-machine (Numerical Control Machine). A scraper is then pulled
over the deposited metallic powder so that a layer of the metallic powder
with the required thickness for further processing is produced. The
metallic powder is then melted in the layer at the boundary of the mold
cavity 5', the feeder ducts 7' and the coolant ducts 8'. The molten
powder is fused into a solid structure limiting the mold cavity 5',
feeder ducts 7' and coolant ducts 8'. The machine table is then lowered
by a distance corresponding to a thickness of a layer such that an
additional layer of metallic powder may be applied in the casing. These
steps are repeated until the lower part 3' of the injection mold 1' is
completed.

[0044] A supporting structure may be produced in the metallic powder
material during production of the lower part 3' of the injection mold 1'.
Once the lower part 3' of the injection mold 1' has been completed, the
powder remaining in the mold cavity 5', feeder ducts 7' and coolant ducts
8' is dumped. The finished lower part 3 of the injection mold 1' is
illustrated in FIG. 10. The upper part 4', as shown in FIG. 9, may be
built up using a method similar to the building of the lower part 3' of
the injection mold 1'. For example, a casing corresponding to a shape of
the upper part 4', including a second portion of the mold cavity 5', is
filled with a metallic powder that is melted and reapplied layer by layer
fusing the molten powder into a solid structure limiting the mold cavity
5' and the ducts for air and material outlet 6'. When the upper part 4'
the injection mold 1' have been completed, the powder remaining in the
ducts for air and material outlet 6' is dumped.

[0045] As illustrated in FIG. 7, the lower and upper parts 3', 4' are
built on the base portion 9' so the lower and upper parts 3', 4' together
form the mold cavity 5'. The lower part 3' may be positioned on the base
plate 9' such that the first portion of the mold cavity 5' is open in a
direction away from the base plate 9'. The upper part 4' may then be
placed in a corresponding position such that the second portion of the
mold cavity 5' faces the first portion of the mold cavity 5' and is
aligned therewith. Similarly to the injection mold system 1, a metal
structure 14' and two metallic inserts 12' may be inserted into the
injection mold 1' before the lower and upper parts 3', 4; of the
injection mold system 1' are fixed closed. The metal structure 14 is used
to support a product 11' and the metallic inserts 12' into which threads
can be subsequently machined. The base plate 9', along with the two-part
mold 13' built thereon, is removably attached to a machine interface
plate 17' of an injection molding machine 21. As described above in
regard to the injection mold system 1, feeder ducts 7' for supplying the
molten material to the mold cavity 5', a duct for air and material outlet
6' from the mold cavity 5' and coolant ducts 8' for a cooling liquid
during cooling off the injected molten material are produced in
communication with respective channels in the base plate 9' so that the
injection mold 1' requires no subsequent processing. Additionally, the
diameters of the feeder ducts 7' may be made sufficiently large so that
sprues 15' are formed by the solidified cast material which firmly hold
the molded product 11' to the injection mold system 1' during subsequent
machining.

[0046] The injection mold system 1' may be used in a substantially similar
manner to that described above in regard to the injection mold system 1'.
As shown in FIG. 7, a molten material, e.g. polyether ether ketone
(PEEK), a reinforced plastic or an injectable metal alloy is injected
into the injection mold 1' through the two feeder ducts 7' and into the
mold cavity 5'. The mold cavity 5' is completely filled with the molten
material with a portion thereof extending into the duct for air and
material outlet 6'. After the injection step has been completed a cooling
liquid is pumped through the coolant ducts 8' so that the injected molten
material is cooled off and the product 11' is formed.

[0047] After cooling off the injected molten material and forming the
product 11', the upper part 4' of the injection mold 1' is removed.
Subsequently, the lower part 3' of the injection mold 3' is machined away
or milled using, for example, a milling cutter. A portion of the lower
part 3' of the injection mold 1' is removed to completely expose the
product 11'. The lower part 3' of the injection mold 1', which is still
fixed to the base plate 9' may be mounted on e.g., a machine interface
plate 17 of a milling machine.

[0048] Similar to the first embodiment illustrated in FIGS. 1 to 6, the
step of machining the product 11' can be performed on the same milling
machine as used during the previous step where the lower part 3' of the
injection mold 1' was machined. The machining of the product 11' includes
the cutting of threads into the metallic inserts 12' and producing a
smooth surface on the whole product 11' using, for example, a milling
tool. During machining, the product 11' is firmly held in the remaining
part of the lower part 3' of the two part mold 13' via integrally cast
sprues 15' which extend from the product 11' within the feeder ducts 7'.
After the product 11' has been machined as desired, the product 11' may
be cut from the sprues 15' so that only the finished product 11' remains.

[0049] Although the invention and its advantages have been described in
detail, it should be understood that various changes, substitutions, and
alterations can be made herein without departing from the spirit and
scope of the invention as defined by the appended claims. Moreover, the
scope of the present application is not intended to be limited to the
particular embodiments of the process, machine, manufacture, composition
of matter, means, methods and steps described in the specification. As
one of ordinary skill in the art will readily appreciate from the
disclosure of the present invention, processes, machines, manufacture,
composition of matter, means, methods, or steps, presently existing or
later to be developed that perform substantially the same function or
achieve substantially the same result as the corresponding embodiments
described herein may be utilized according to the present invention.

[0050] It will be appreciated by those skilled in the art that various
modifications and alterations of the invention can be made without
departing from the broad scope of the appended claims. Some of these have
been discussed above and others will be apparent to those skilled in the
art.